That would of course be a lot different if we were belting down the A2 after a night in London going back home, but then the argument becomes moot because an Uber would happily take me home for the cost of half a tank of diesel where a black Cab would likely turn his light off then try to run me over rather than risk having to drive back without some mug punter to talk to/fleece for 80 bar

Most cars are much, much faster than black cabs. However, that is completely irrelevant as you can't get much speed up on a London Road in any case.

Same argument applies to your 'car crashed' retort. A crash at 30mph isn't going to kill me whatever car I'm in, so I'd rather be in a superior one - even a Mondeo or a Passat - than in a shitty black Cab.